1. Field of the Invention
The invention relates to internal combustion engines having the cylinders parallel to the shaft; more particularly, it relates to such axial cylinder engines, which use a cylindrical cam driven by roller followers attached to the pistons.
2. Description of the Prior Art
Many styles of axial cylinder internal combustion engines wherein the cylinders are parallel to, and equidistant from, the main engine shaft have been developed. Such machines have been known in the past as barrel engines or simply round engines, because their distinguishing characteristic is the circular or cylindrical arrangement of the elements. Frequently, these engines are designed for conventional four cycle operation. A cylindrical cam couples the pistons to the drive shaft. Where ridge cams are used, cam followers on each piston track the radial surfaces of the rotating cam.
These engines contain inherent advantages of low cost, light weight, and small volume. Nevertheless, they have not been commercially successful. In axial cylinder engines, sharp load reversals are experienced by the reciprocating pistons, and such load reversals, particularly where accompanied by excessive clearance requirements, result in hammering contact at mating surfaces, noisy operation, and short life. To a large extent, the past deficiencies of these engines can be traced to the relatively large variations in the clearances among the mating parts due to manufacturing tolerances, thermal distortions and wear.
Rotary valves are well adapted for use with axial cylinder engines. They are simple and also compatible from the standpoint of low cost, high volumetric efficiency and quiet operation. While useful in a variety of rotary engines and developed in many forms, here too, no suitable engines have been produced, at least partly due to the excessive friction, sealing problems, overheating, and scoring which may be attributed to inadequate distribution of lubricants to the rubbing surfaces.
Those familiar with engine development also recognize the many attempts and the partial success that has been experienced in the utilization of stratified charges. Stratified charges are employed to achieve maximum ignition characteristics, efficient use of fuel, and complete combustion. Typically, the stratified charges are supplied to separate or distinct sections of a combustion chamber such that a richer fuel mixture will be ignited within a first section and a leaner mixture will thereafter be ignited in the second.